Sensors have been widely used in intelligent lighting control systems. For example, ceiling or wall mounted occupancy sensors can detect activities within a specified area and send signals to a lighting controller. By doing this, the system can automatically turn lights on when someone enters an area or turn light off soon after the last occupant has left, to reduce energy use and provide added convenience.
Another example of intelligent lighting control is daylight harvesting, which concerns using daylight to offset the amount of electric lighting needed to properly light a space in order to reduce energy consumption. This is accomplished by dimming or switching electric lighting in response to changing daylight availability in the space, which is for example detected by a ceiling mounted light level sensor.
One major inconvenience of incorporating sensors in a lighting control system is to establish the connections between the sensors and the light points. Currently this is done in one of two ways.
A first method uses a wired connection between a sensor and a lighting controller which is either a central system controller or a distributed controller at the light point. This brings difficulties for retrofit applications.
A second method uses wireless connections for easy retrofit. However, this adds complexity to the commissioning, i.e., pairing between sensors and light points. To solve this, intelligent luminaires with integrated sensors have been developed in recent years.
For example, LED luminaires are known with integrated occupancy sensors for maximizing energy efficiency, and luminaires are known with integrated motion sensors and daylight sensor. By using intelligent luminaires with built-in sensors instead of separately installed luminaires and sensors, the installation and commissioning costs of lighting control systems are reduced. However, this kind of luminaire-integrated control also has disadvantages.
Firstly, the design complexity of the luminaires is increased. Different sensors may have analog signals (e.g., a continuous voltage signal) or digital signals output through different data interfaces (e.g., SPI and I2C used for digital sensors). This must be taken into consideration by the luminaire manufactures when adding sensors into their luminaires. When it is necessary to replace an already integrated sensor with a different model (e.g., from a different supplier), redesigns are sometimes unavoidable.
Secondly, a lighting system using luminaires with built-in sensors has limited flexibility. The sensor placement is tightly bound by the luminaire placement. For example, a storage room having luminaires with temperature sensors may be redesigned into a meeting room. The temperature sensing function is no longer needed and occupancy detection is instead required. The user has to replace the luminaire which is expensive and inconvenient.
Thus, current intelligent luminaires with built-in sensors have the disadvantages of high design complexity and low flexibility.
D1 EP2770804A1, D2 WO2009/029960A2, D3 US2011/057583A1 and D6 US2012/080944A1 are all about wireless communication with lamps.